This invention relates generally to camshafts for reciprocating piston engines and more particularly to method of making a camshaft where the cams and shaft are produced as individual elements and are fastened together forming the camshaft.
One method of manufacturing camshafts involves forming the cams separately by methods such as powdered metallurgy. The cams are then fastened to a hollow tube using known fastening processes, such as welding, brazing or expansion of the hollow tube. Bearing or journal surfaces are machined onto the hollow tube between cams. Another method of attaching the cams, described in U.S. Pat. No. 4,858,295, leaves a plurality of projections on the outside of the hollow tube between cams. These projections must be removed in order to form the journal surfaces.
The displacement of material caused by an expander tool during expansion of the hollow tube induces work hardening and stress into the tube. Limiting work hardening reduces the risk of failure due to tube splitting.
The foregoing illustrates limitations known to exist in present camshafts. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.